About: http://webisa.webdatacommons.org/166089158

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	They contain asphaltenes, resins, sulfur, and such metals as vanadium and nickel, which results in an increase in density.
http://www.w3.org/ns/prov#wasQuotedFrom	britannica.com